Subclinical central neuropathy in type II diabetes mellitus

ABSTRACT

To evaluate central nervous system neuropathic changes in patients with type 2 DM with and without peripheral neuropathy. Thirty patients with type 2 DM were included. They were equally divided into two groups those with clinical and electrophysiological findings of peripheral neuropathy [Group 1], and those without [group 2]. Fifteen healthy individuals were included as a control [group 3]. All groups were subjected to fasting plasma glucose, glycated hemoglobin [HbA1c] and other necessary tests, in addition to the electrophysiological study including Somatosensory evoked potentials [SEP], motor evoked potentials [MEP], visual evoked potentials [VEP] and brainstem auditory evoked potentials [BAEP]. Group 1 had statistically significant higher mean values of fasting plasma glucose, HbA1c, urinary albumin excretion [UAE] and serum creatinine compared with group 2. Both diabetic groups had similar changes in VEP P100 latency and its amplitude, MEP central motor conduction time, amplitude percentage quotient and duration of the MEP, and BAEP wave II latency, with statistically significant differences compared to healthy controls. There was a statistically significant delay in all of the BAEP waves' interpeak latencies only in group 1. The other tested parameters of central neuropathy showed statistically significant differences between all studied groups. A statistically significant positive correlation was observed between some of the studied parameters of central neuropathy in diabetic patients and each of the patient age, duration of diabetes, HbA1c, serum total cholesterol, serum triglycerides and UAE. Central neuropathy in type 2 diabetics is not uncommon even in absence of peripheral neuropathy. It is related to the patient's age, duration of diabetes, glycated hemoglobin value, dyslipidemia and diabetic nephropathy. The use of more than one modality of the electrophysiological tests can buffer the fallacies of a single mode